Green tea good for arteries4th July 2008
Drinking green tea has a fairly immediate effect on blood vessels, and may help to prevent heart disease, a new study has shown.
Writing in the latest issue of European Journal of Cardiovascular Prevention and Rehabilitation, a team of researchers at the Athens Medical School in Greece said they had found that consumption of green tea rapidly improves the function of endothelial cells, which line the circulatory system.
Endothelial dysfunction is a key event in the progression of atherosclerosis, or "hardening of the arteries".
The team, led by Nikolaos Alexopoulos of the 1st Cardiology Department, carried out a randomised trial involving the diameter measurement (dilatation) of the brachial artery of healthy volunteers on three separate occasions - after taking green tea, caffeine, and hot water (for a placebo effect).
The measurements were taken at 30, 90 and 120 minutes after consumption. This measurement was chosen because it is an important indicator of cardiovascular risk, and gives an idea of how well the person's endothelial cells are working.
Green tea produced a peak increase of 39% 30 minutes after consumption, indicating that the drink has a rapid and measurable effect on the functioning of the endothelial cells.
The groups who took caffeine and hot water showed no significant change in their measurements.
The study is the first to show that green tea is associated with a short-term beneficial effect on the large arteries. Black tea has also been associated in previous studies with similar effects. Yet another study has already shown that green tea reverses endothelial dysfunction in smokers.
But the antioxidants believed to be so beneficial in black tea are probably more potent in green tea because the tea leaves - long used as part of traditional Chinese medicine - have undergone no process of oxidisation.
Investigator Charalambos Vlachopoulos said the findings have important clinical implications, and could demonstrate an even better effect on cardiovascular morbidity for green tea than has already been linked to black tea.
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